Central Retinal Artery Occlusion (CRAO - Acute Ocular Infarction)
Acute embolic occlusion of the central retinal artery causing immediate retinal ischemia, analogous to an acute ischemic stroke (Ocular Stroke).
Article Table of Contents
1. Comprehensive Overview
Central Retinal Artery Occlusion (CRAO) is an acute ischemic infarction of the inner retina and a true ocular and neurological emergency, classified as an acute ischemic stroke variant.
Pathophysiology: The central retinal artery is an end-artery branching from the ophthalmic artery. Occlusion is primarily caused by an embolus originating from ipsilateral carotid atheroma (cholesterol Hollenhorst plaque, calcific cardiac valve plaque, or fibrinoplatelet thrombus).
Pathognomonic Funduscopic Appearance: Within minutes of arterial cessation, ischemic intracellular edema renders the retina opaque, edematous, and milky-white. The foveola, possessing only photoreceptors and thin RPE nourished by the underlying choroid, stands out prominently as a classic 'Cherry-Red Spot'.
The Critical Ischemic Window: Primate models establish that irreversible ischemic retinal ganglionic death occurs within 90 to 240 minutes of total arterial occlusion, making immediate hyperacute intervention mandatory.
2. Symptoms & Warning Signs
If you observe any of the following symptoms repeatedly, an eye exam is strongly recommended:
- Sudden, catastrophic, painless, profound monocular visual loss occurring over seconds
- Vision reduced abruptly to counting fingers, hand motion, or light perception
- History of transient monocular visual loss ('Amaurosis Fugax' - ocular TIA) in preceding days/weeks
- Completely white and quiet eye externally with no discharge or conjunctival injection
- Marked Relative Afferent Pupillary Defect (Marcus Gunn pupil / RAPD)
3. Causes & Risk Factors
- 1Carotid artery atheroembolism (cholesterol Hollenhorst plaques, calcific, or platelet-fibrin emboli)
- 2Cardiogenic embolism (atrial fibrillation, valvular vegetations, mural thrombi, patent foramen ovale)
- 3Giant Cell Arteritis (Temporal Arteritis - GCA): Arteritic CRAO in elderly patients (>60 years), a bilateral sight-threatening emergency
- 4Severe systemic atherosclerosis, arterial hypertension, and dyslipidemia
- 5Thrombophilic coagulation disorders and systemic vasculitides
4. Treatments & Medical Management
5. Prevention & Daily Eye Care Advice
- Regular screening of carotid arteries and cardiac rhythm in patients with cardiovascular risk profiles
- Strict compliance with antiplatelet therapy (Aspirin, Clopidogrel), statins, and antihypertensives
- Treating any episode of transient monocular visual loss (Amaurosis Fugax) as a medical emergency requiring same-day stroke workup
- Anticoagulation management for non-valvular atrial fibrillation
6. When to Seek Emergency Eye Care
Visit an immediate eye emergency center if you experience any of the following critical indicators:
- ⚠Sudden, instantaneous, painless loss of vision in one eye (immediate 911 / emergency room alert)
- ⚠Transient blackouts or graying of vision lasting a few minutes before recovering
- ⚠Temporal headache, scalp tenderness, or jaw claudication on chewing in elderly patients (GCA alert)
7. Frequently Asked Questions
Q:Why is retinal artery occlusion considered a stroke?
Because the central retinal artery shares its vascular origin with the cerebral circulation. A retinal embolus indicates active thromboembolic disease in the carotid arteries or heart, carrying a high risk of subsequent ischemic cerebral stroke within weeks if left uninvestigated.